The Core Laboratory will provide individual investigators with cell products and assays which will be needed routinely and which are better performed in a centralized facility. They will also supply the various projects with the in vitro assays for bone resorption and bone formation with which our group has extensive experience over the years. The specific activities of the core will include separation of bulk quantities of cells and assays for bone resorption. The personnel of the Core Laboratory will be highly integrated with personnel from a number of projects in the proposal. Most of the projects proposed have, as one of their components, the use of a bioassay and media harvested from cultured cells. The Core Laboratory would provide these services in an efficient, reproducible and cost saving manner.